Editing Subtraction (section)

===Trade first===
A variant of the American method where all borrowing is done before all subtraction.<ref>[https://sites.google.com/a/oswego308.org/msimester/home/math/algorithms/subtraction The Many Ways of Arithmetic in UCSMP Everyday Mathematics] {{Webarchive|url=https://web.archive.org/web/20140225135251/https://sites.google.com/a/oswego308.org/msimester/home/math/algorithms/subtraction |date=2014-02-25 }} Subtraction: Trade First</ref>

Example:
<gallery>
File:Trade First Subtraction Step 1.JPG|1 − 3 = not possible.<br>We add a 10 to the 1. Because the 10 is "borrowed" from the nearby 5, the 5 is lowered by 1.
File:Trade First Subtraction Step 2.JPG|4 − 9 = not possible.<br>So we proceed as in step 1.
File:Trade First Subtraction Step 3.JPG|Working from right to left:<br>11 − 3 = 8
File:Trade First Subtraction Step 4.JPG|14 − 9 = 5
File:Trade First Subtraction Step 5.JPG|6 − 4 = 2
</gallery>